Method of sizing bells and spigots of steel-cylinder concrete pipe



Jan. Z3, 1962 K. E. J Es 3,017,695 METHOD OF' SIZING BE S AND SPIGOTS OF ST -CYLINDER CONCRETE PIPE iled Jan. s1, 1957 .Ffa j.

Z756. c?. J6

Y .Ww Y,

J/G 5 IN VEN R.

gw/M

United States Patent G1 Kenneth E. James,l Covina,l Calif., assignor to United' Concrete Pipe` Corporation, Baldwin Park, Calif.,V av

corporation of California FiledJn. 31, 1957, ser. No. 631,381V 2 Claims. (Cl. 29-523)` This invention relates to aV method of sizing the'bellsvv and spigotsofi steel-cylinder concrete pipe, and particularly the bells and spigots of pipe, wherein' a gasket or sealing ring `is disposed in al metallic channel on the spigot and which,vwhen the bell and spigot are assembled -together, is positioned against a metallic lining on the interior of the bell.

Explanatory of the present invention, in the construction of that type of concrete pipe to which this invention relates the customary procedure is to rst form a sheet metalv tube which extends. from end to end of the pipe. This tube frequentlyis linedwith a self-hardening cementitious lining that may be applied centr-ifugally. On the exterior of the tube there may beapplied a self-hardening` concrete coating in which thereV may or may not beV Where the pipe joint'between.

metallic reenforcements. adjoining sections of pipe is to have a rubber gasketv or sealing ring interposed between the end of the spigot and theinterior of the bell the sheetv metal tubev is ared at the interior of the bell so as to be exposed therein for engagement by the rubber gasket. the pipe has `an endless ring-like channel applied around the-exterior of the tube, and this channel provides a seat for the gasket or sealing ring.

It is desir-able that the portion of the seel'tube which forms a metallic lining on the interi-or of the bell be reenforced or backed up' by a similar endless ring-like channel.

In constructing pipe of this character endless rings are telescoped over the ends of the steel tube. In the case of' the spigot end, the endless ring is usually in the form of a'channel designedto receive` a rubber gasket. In the case` of the bell end the ring frequently is in the form of a. channel but mayy have other shapes. the ring. andthe steel tube or cylinder is relatively loose when the ring is initially applied.

desirable limits. when telescoped over the metallic tube or cylinder may be slightly oversized.y Also, the flared end of the tube onthe interior. ofthe bell may be slightly undersized. If this is theV case insertion of the spigot into the bellV is rendered dii'cult. If the reverse: is true, namely that the spigot channel is undersized and the. flared end of the tube or cylinder within thebell is oversized the joint may be so loosethattherubber gasket isincapablef'of maintaining .an yadequate seal.

It` isaprimary object of the presentinvention to pro vide a novel method by which the channel on the spigot and the ilared end of the tube that is surrounded by the channel in the bell canbe seized relatively to each other so as to properly. tit withinacceptable tolerances.

Briefly stated, the method. consists' oil-assembling the channel and the tube togethertelescopieally at each end of the pipe Kand then expanding. the tube and channel to a limited extent beyond th'eelasticlimits or yield points of the metals of which these parts are formed. After the elastic limit or yield point yhas been exceeded the expansion, is continued, slightly beyond the nominal sizes that these parts are to iinallyhave. The expanding means is then removed and even though the elastic limit of the material has been exceededthere is still a slight amount of vspringbaelt orcontrac-ti'on. However, this Kamount of The spigot end of' The lit betweenA y In relatively largeV sizes ofpipe i-t is difficult to maintain tolerances within In other words, the spigot channel;

ice

springback is comparatively uniform with avgiven ma` terial` from the expanded condition: wherein the. yield point or elastic limit has been exceeded. Consequently,y even though the metal in theV bell springs back or con'- tracts slightly from its oversized condition, the returniI being substantially uniform, causes the interior dimension of the bell .to be substantially uniform. The same is, true of the spigot. Consequently, the external size` off the channel on the spigot can be caused to't the ilared interior of the tube in the bell within acceptable tolerancesf which would be very difficult to maintain if' these parts olff the pipe were otherwise constructed.

As the channels on the spigot and on the bell IarelooseL; ly telescoped onto the ends of the tubing in thez courseof assembly there may be a small amount of clearance-` between these parts which it is desirable to: avoid; Ther present method of sizing isA also advantageous inthati the expansion of the tube in the course of expanding it and the channel beyond the elastic limitsv or yield: points of these parts causes the clearance to bez auto; matically taken up and eliminated. Consequently, the: channels at the bell and at the spigot will tightly t around? the ends of the tubeV in the completed structure even? though they were loose with respect to each other inthe; course of assembly.

With the foregoing and other objects in View, which? will be made manifest in the following detailed descrip# tion `and specilically pointed outinthe appended claims,v reference is had to the accompanying drawings-for an'.l illustrative embodiment of the invention, wherein:

FIGURE l illustrates a portion of that endf ofthe-f metallic tube of a reinforced concrete pipe thatv isY to! form the bell end of the pipe showing the channel used? at the end of the pipe in 'assembled relationship there.- with;

FIG. 2 illustrates the same portion ofthe tube and-its@ channel after the tube and channel have been expanded! beyond the elastic limit and -after the expandingl means has been withdrawn;

FIG. 3 is a View similar to FIG. l, but illustrating thespigot channel in assembled relationship withl the' spigot. end of the tube;

FIG. 4 is a view similar to FIG. 3, but illustratingf this end of the tube and the spigot channel-as havin-gV been expanded; and

FIG. 5 is a sectional viewv of a concrete pipe joint,, the `bell `and spigot of which have had their metalliere enforcements sized in accordance with the 'present` invention.

Referring to the `accompanying drawings wherein similar reference characters designate similar partsf throughout, lll indicates -a metallic tube which may bei formed of mild steel and which extends from end-.toi end of a section of concrete pipe. This tube may ulti-'-` mately have a. concrete lining indicated at 11., applied'- therein centrifugally or otherwise. It may also ulti# mately have an outer coating of concrete, 12r applied thereto within which helically wound rods or wires-13 are embedded.

On that end of the tube l0 which is ultimately to for-nr the bell end of the pipe section there isv teles'coped anV endless channel 14. This channel may also be formed of mild steel, and in order to facilitate assembly o'f the' channel 14 with lthe tube 10 there may be a clearance indicated `at 15 between the channel and the end-of the? tube.

After the channel and tube have been assembled an expander, not shown, is placed in the end of the tube'I toV expand the tube outwardly or flare it outwardly as indicated at 16. That portion of the tube. whichisbeyondf the end of the lining 11 and which is indicated atl'fmay' also be expanded into afconditionzthat is approximately cylindrical. Outwardly of this cylindrical portion the tubing may again be flared as indicated at 18.

In accordance with the present invention this end of the tube and the channel ring 14 are expanded beyond the elastic limit or yield point of the materials of which the tube and ring are formed. In the course of expansion of the tube the clearance 15 is taken up as is illustrated in FIG. 2, and both materials are expanded beyond the yield point. Preferably, the tube and ring are expanded to an oversize condition wherein the interior diameter of the cylindrical portion is about 0.1%, measured either diametrically or circumferentially, greater than the nominal size that the internal diameter of the portion 17 is to ultimately have. When the yield points of the materials have been exceeded, I find that the metal still possesses some springback and this springback usually measures from 0.085% to 0.115%. Consequently, when the expander has been removed from the interior of the tube the tube and ring will return or contract approximately 0.1% from the oversized or overstressed condition. This springback with a given material is substantially uniform from the overstressed condition so that the final internal size of the portion 17 is uniform within acceptable tolerances, in a similar manner, on the spigot end of the tube 10 there is -applied a spigot channel indicated at 19 which may be loosely applied so that there is present a clearance 20. This end of the tube is likewise expand ed so that the clearance 20 disappears or is taken up in the course of the initial expansion of the tube 10. The end of the tube 10 and the ring 19 are both expanded beyond the elastic limits of the materials and as above explained, about 0.1% greater than the final nominal external diameter of the spigot. When the expander is removed the ring 19 and this end of the tube 10 will both spring back or contract approximately 0.1% so that the linal external diameter of the spigot ring 19 is Within such a tolerance that it can be telescoped into the bell end of the pipe when the bell and spigot of adjoining sections are mutually assembled together. Consequently, when the rubber sealing ring 21 is positioned in the channel 19 for the purpose of Ifunctioning as a gasket the fit between the exterior of the spigot and the interior of the bell will be sutliciently close so that the sealing ring will function properly.

The reference numeral 22 indicates grout that m-ay be applied over the joint after the ybell and spigot have been assembled together.

It will be appreciated that the above-described method provides a means whereby the bell and spigot can be sized with a high degree of accuracy and whereby no expensive machining operations are required to make these portions of the pipe lit each other properly.

While the invention has been developed primarily in connection with the metallic structures in the ends of concrete pipe it may be employed wherever it is desired to manufacture two metallic parts which are ultimately to telescopically t together, and wherein either of said parts are made up of two parts that are loosely telescoped one upon the other.

In carrying out the invention it is not necessary that both parts that are initially telescoped together in the course of assembly be stretched or expanded beyond the elastic limits or yield points of both parts. In other words, considering FIGS. 3 and 4, the tube 10 within the endless channel 19 may be expanded beyond the elastic limit or yield point of the material of the tube 10, but without exceeding the elastic limit or yield point of the channel 19. In this event when the expander is removed the channel 19 may tend to return to its initial condition because of the fact that its yield point has not been exceeded. However, as the yield point of tube 10 has been exceeded the clearance 20 will be taken up and a close lit maintained between the tube 10 and the endless ring. Similarly, in the case of the bell the material of the tube 10 may be expanded beyond its yield point but the expansion of the channel 14 need not necessarily have been expanded beyond its elastic limit. Such a construction may be resorted to in the event that the rings are precisely made. However, if the rings are not precisely made then both the tube and the endless ring are expanded beyond their elastic limits and upon having some springback these parts will ultimately have the proper size within the desirable tolerances.

In describing the invention above, reference has been made to the use of mild steel -as this is the material usually employed for these parts in the construction of concrete pipe. It Will be appreciated that the invention is not restricted thereto but may be employed with other metals and materials which may have different elastic limits or yield points and which may possess different springbacks after the elastic limit or yield point has been exceeded by the expansion. With different materials some laboratory work may be necessary to determine the amount of springback that occurs after the elasti limit or yield point of the particular material selecte has been exceeded.

Various changes may be made in the details of con, struction without departing from the spirit and scope of the invention as delined by the appended claims.

I claim:

1. The method of sizing two annular metal parts with reference to a nominal diameter which parts are ultimately to be telescoped together and which parts each consists of two annular metal sections concentrically arranged which consists of loosely arranging the metal sections of each part in concentric relationship, expanding the inner section of each part independently of the section of the other part into engagement with the outer section of its part to take out all looseness between the sections, continuing the expansion of the inner section sutiiciently so as to create an overstressed condition in the metal thereof occasioned by exceeding the elastic limit or yield point of the metal from which the inner section is formed, and also suiciently so that the ex ternal diameter of one part and the internal diameter of the other part exceed the nominal diameter by approximately the same amount, and discontinuing and removing the expansion effort.

2. The method of sizing two annular metal parts' lwith reference to a nominal diameter which parts are ult mately to be telescoped together and which parts also each consists of two annular metal sections concentrically arranged which consists of loosely arranging the sections of each part in concentric relationship, expanding the inner section of each part independently of the sections of the other part into engagement with the outer section to take out all looseness between the sections, continuing the expansion of the inner section of each part suiciently so as to create an overstressed condition in both sections of each part occasioned by exceeding the elastic limit or yield point of the metal from which the sections formJ ing the parts are formed, and also suflciently so that the external diameter of one part and the internal diameter, of the other exceed the nominal diameter by approxi-I mately the same amount, and discontinuing `and removI ing the expansion effort.

References Cited in the le of this patent UNITED STATES PATENTS 1,720,366 Langenberg July 9, 1929 1,953,665 Wallace Apr. 3, 1934 2,216,833 Barry Oct. 8, 1940 2,263,714 Bloomield et al Nov. 25, 1941 2,449,428 Timmons Sept. 14, 1948 2,493,127 Franck Jan. 3, ()y 2,569,612 Laurent Oct. 2, 1951 FOREIGN PATENTS 229,114 Germany Dec. 2, 1910 676,569 Great Britain July 30, 1952 689,043 Great Britain Mar. 18, 1953 

